I am a relative ubuntu newbie and i have a huge prob on my hand

i have 2 harddisk a 40 and 160 gb.both are ntfs formatted

ubuntu recognise my 40 gb hd which has 2 part 1 for xp and the other for ubunutu
but the 160gb harddisk is shown as a scsi device in computer and when i open it it shows "cannot mount file"

so can anybody help me
thanks.